In various applications of electrical power cable, it is necessary to carry electricity from a dirty outside environment to a clean, uncontaminated environment, or vice versa, with such an interface often experiencing rapid pressure changes. For example, in oil wells, connectors are attached to the ends of penetrators and this attachment can experience rapid high pressure changes. If voids exist in the attachment of the connector with the penetrator, hydrostatic pressure will try to force contaminating liquids into the connector, thus leading to poor electrical performance or failure.
Accordingly, in these environments, the main problem associated with the connectors of penetrators is to avoid disruption of the electrical connection due to leakage in the connector and exposure of the electrical conductors to oil, brine and other oil well fluids. In addition, these connectors must be operable in environments subject to rapid increases in pressure such as from 1,000 psi to 3,000 psi when valves and pumps in the system are opened or closed or energized or de-energized.
While various prior art connectors used in these environments are known, they have numerous disadvantages. First, many of these devices have precisely molded mating parts that require careful installation to control how tightly the mating parts should be screwed together. If these parts are not adequately tightened, voids remain, and if overtightened, their seals are distorted and cannot function properly. Other designs employ mated elastomeric parts separated by dielectric grease. Again, too much or too little grease can cause problems. Moreover, common to both of these approaches is the problem of unequal amounts of compression between a steel part and an elastomeric part when there is a sudden increase in pressure. Accordingly, when there is a sudden increase in pressure, an elastomeric insulation layer on an electrical cable and an elastomeric seal will experience a sudden momentary reduction in volume due to the collapse of microvoids within the elastomer, causing volumetric compression of the polymer itself. This volume reduction is a transient condition because the elastomer soon absorbs sufficient high pressure fluids to restore stress distribution within the elastomeric matrix, thereby allowing the elastomer to expand back to its natural size. Thus, dirty contaminated outside fluid can momentarily leak between the seal and the cable to the inside of the connector in these prior art devices.
Examples of these prior art devices which utilize various sealing assemblies are disclosed in the following U.S. Pat. Nos.: 1,795,541 to Brownell; 1,904,250 to Purvis; 2,017,994 to Spang; 2,331,615 to Meyer; 3,279,806 to Bialkowski; 4,500,119 to Geberth, Jr.; and 4,652,024 to Krohn.
This invention addresses this problem in the art, along with other needs which will become apparent to those skilled in the art once given this disclosure.